Starting and operating control system for free piston engine hydraulic pump as a power plant of a hydrostatic driven vehicle



Nov. 12, 1963 A. E. w. JoHNsoN ETAL 3,110,152

STARTING AND OPERATING CONTROL SYSTEM FOR FREE PISTON ENGINE HYDRAULIC PUMP AS A POWER PLANT 0F A HYDROSTATIC DRIVEN VEHICLE Filed May l. 1961 12 Sheets-Sheet l HYDRAULIC Nov. 12, 1963 A. E. w. JOHNSON ETAL 3,110,152 STARTING AND OPERATING CONTROL SYSTEM FOR FREE PISTON ENGINE HYDRAULIC PUMP AS A POWER PLANT OF A HYDROSTATIC DRIVEN VEHICLE 12 Sheets-Sheet 2 Filed May l, 1961 RMN d MW.

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NOV. 12, 1953 A. E. w. JOHNSON E'rAL 3,110,152

STARTTNG AND OPERATING CONTROL SYSTEM FOR FREE PIsToN ENGINE HYDRAULIC PUMP AS A POWER PLANT OF A HYDROSTATIC DRIVEN VEHICLE Filed May l, 1961 12 Sheets-Sheet 3 START NAX/HUMPUWF .STaP

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NOV' 12, 1963 A. E. w. JOHNSON ETAL 3,110,152

STARTING AND OPERATING CONTROL SYSTEM FOR FREE PISTON ENGINE HYDRAULIC PUMP AS A POWER PLANT OF A HYDROSTATIC DRIVEN VEHICLE Filed May 1, 1961 12 Sheets-Sheet 4 3,110,152 PIsToN Nov. 12, 1963 A. E.w..1oHNsoN ETAL STARTING AND OPERATING CONTROL SYSTEM FOR FREE ENGINE HYDRAULIC PUMP AS A POWER PLANT 0F A HYDROSTATIC DRIVEN VEHICLE 12 Sheets-Sheet 5 Filed May 1, 1961 MQW mhd .m i

NOV 12, 1963 A. E. w.JoHNsoN ETAL 3,110,152

STARTING AND OPERATING CONTROL SYSTEM FOR FREE PISTON ENGINE HYDRAULIC PUMP AS A POWER PLANT OF A HYDROSTATIC DRIVEN VEHICLE Filed May 1, 1961 12 sheets-sheet e MHAX/HUM POWER START START ma),

NOV 12, 1963 A. E. w. JoHNsoN ETAL 3,110,152

STARTING AND OPERATING CONTROL SYSTEM FOR FREE PISTON ENGINE HYDRAULIC PUMP AS A POWER PLANT 0F A HYDROSTATIC DRIVEN VEHICLE Filed may 1, 1961 12 sheets-sneer? START NOV- 12, 1963 A. E. w. JoHNsoN ETAL 3,110,152

STARTING AND OPERATING coNTRor. SYSTEM FOR FREE PIsToN ENGINE HYDRAULIC PUMP AS A POWER PLANT OF A HYDRosTATIc DRIvEN VEHICLE 12 Sheet's-Sheet 8 Filed May l, 1961 QMS,

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www. mix mmh] www@ A. E. w. JoHNsoN ETAL PIOJSZ ENGINE HYDRAULIC PUMP AS A POWER PLANT OF Nov. 12, 1963 STARTING AND OPERATING CONTROL SYSTEM FOR FREE A HYDROSTATIC DRIVEN VEHICLE 12 Sheets-Sheet 9 Filed May 1, 1961 doku NOW 12, 1963 A. E. w. JoHNsoN ETAL 3,110,15

STARTING AND OPERATING CONTROL SYSTEM FOR FREE PISTON ENGINE HYDRAULIC PUMP AS A POWER PLANT 0F- A HYDROSTATIC DRIVEN VEHICLE med may 1. 1961 12 sheets-sheet 1o f2: /Ez

Lk ux/Man Pon/ER MAX/MUM Pou/EP sraP R MCD' MA/@Mc A. E. W. JOHNSON ETAL G AND OPERATING CONTROL SYSTEM FOR FREE PISTON ENGINE HYDRAULIC PUMP AS A POWER PLANT OF 12' SheeizfhSheem.l 1l

Nov. 12, 1963 STARTIN A HYDRosTATIc DRvEN VEHICLE Filed May l, 1961 z 233 Jn/mfom 225 @Frizald Zclfojzson do/zn wz ff fffarza 3,1 10,152 PIsToN Nov. 12, 1963 A. E. w. JOHNSON ET AL STARTING AND OPERATING coNTRor. SYSTEM EoR FREE ENGINE HYDRAULIC PUMP AS A POWER PLANT OF A HYDROSTATIC DRIVEN VEHICLE 12 Sheets-Sheet 12 .Filed May 1, 1961 United States Patent() M STARTING AND GPERATENG CUNTRL SYSTEM FOR FREE RESTON ENGINE HYDRAULlC PUMP AS A PGWER PLANT F A HYDROSTATIC DRIVEN VEHICLE Arnold E. W. lohnson, @al-r Park, and John F. Swift and Edwin A. Karibu, Chicago, Ill., assignors to linternational Harvester ornpany, Chicago, El., a corporation of New ersey Filed May 1, 1961, Ser. No. 106,969 22 Claims. (Cl. oli-i4) This invention relates to a control system for starting and operating a free piston engine hydraulic pump as a source of power for propelling a vehicle having a hydrostatic transmission including accessories therefor. More lparticularly this invention relates to control means for starting and operating a free piston engine hydraulic pump under variable load conditions wherein the requirements imposed upon the operator thereof are no greater than that required for a vehicle propelled by conventional internal combustion engines such as, for example, diesel engines.

In an application for Letters Patent led by Arnold E. Vi. Johnson, Serial No. 71,949 iiled November 28, 1960, assigned to the same assignor as that of the present application there is described a novel free piston engine lhydraulic: pump as a source of hydraulic power for propelling a vehicle having a hydrostatic power transmission. The present application is directed to a control means for startinU and operating the free piston engine hydraulic pump, described in the above mentioned copending application, under Variable load conditions wherein the complexities of operation by an operator are reduced to a magnitude not greater than that for operating a conventional vehicle such as an agricultural tractor.

A prime object of the present invention is to provide an integrated starting :and operating control means for a free piston engine hydraulic pump as a source of power.

Another important object of the invention is to provide an electro-hydraulic means for starting and operating a free piston engine hydraulic pump as a source of power.

A further object of the present invention is to provide electro-hydraulic control means for operating a free piston engine hydraulic pump power plant under variable loading conditions.

A still further object of the present invention is to provide a means for modulating the pressure of yfuel into a free piston engine hydraulic pump in accordance with the throttle position.

Another object of the invention is to provide hydraulic means for fle-actuation of the fuel injectors for a free piston engine hydraulic pump.

Yet another object of the invention is to provide a reserve source of hydraulic fluid under pressure for immediate available power during a period between the time when the throttle is increased and the time when the free piston engine hydraulic pump attains the speed corresponding to the load and throttle position.

Still a further important object of the invention is to provide a means -for modulating automatically the pumping of a free piston engine hydraulic pump during periods when the load demand is less than the available output at a given speed of the engine.

Another important object of the invention is to provide a starting and operating means for a :free piston engine hydraulic pump as a source of hydraulic pressure for operating a vehicle propelled through a hydrostatic y'transmission wherein the requirements imposed upon an operator are of no greater complexity than re- Faiented Nov. l2, 1R63 ICC quired for operating a conventional internal combustion engine propelled vehicle.

These and other desirable and important objects inherent in and encompassed by the invention will be more readily understood from the ensuing description, the appended claims and the annexed drawings, wherein:

FIGURE 1 is a plan View, in diagrammatic lform, of an agricultural tractor powered by a free piston engine hydraulic pump illustrating the gener-al location of component assemblies of the hydraulic system of this invention.

FIGURE 2 is a side View, in diagrammatic form, of the tractor of FIGURE 1 further illustrating the general location of component assemblies of the hydraulic system of this invention.

'FIGURES 3, 3A, 3B and 3C represent, in schematic form, the general layout of the electro-hydraulic control system of this invention with longitudinal sectional views of the various individual components. FIGURE 3 is positioned at Quadrant I; yFIGURE 3A is positioned at Quadrant II and is the leftward continuation of FIG- URE 3; FIGURE 3B is positioned at Quadrant III and is the lower continuation of FIGURE 3A; and FIGURE 3C is positioned at Quadrant IV and =is the rightward continuation of FIGURE 3B as well as the lower continuation of FIGURE 3. Thus FIGURES 3, 3A, 3B and 3C when positioned in the above mentioned relation forms the layout wherein all components ane shown in the position when the free piston engine hydraulic pump is at rest.

FIGURE 4 is a portion of the components taken from FIGURES 3, 3A, 3B and 3C which are isolated to show the lactuation of certain components occurring during the iirst stage of a series of stages for starting the free piston engine hydraulic pump.

FIGURE 5 is a portion of the components taken from FIGURES 3, 3A, 3B and 3C which are isolated to show the changes in actuation of certain components occurring during the second stage of a series of stages `for starting the free piston engine hydraulic pump.

FIGURE 6 is a portion of the components taken from FIGURES 3, 3A, 3B and 3C which are isolated to show the changes in actuation of certain components occurring during the third stage of a series of stages for starting the free piston engine hydraulic pump.

FlGURE 7V is a portion of the components taken from FIGURES 3, 3A, 3B and 3C which are isolated to show the changes in actuation of certain components occurring during the fourth stage of a series of :stages for starting the free piston engine hydraulic pump.

:FIGURE 8 is a portion of the components taken from FIGURES 3, 3A, 3B and 3C which are isolated to show the changes in actuation of certain components occurring during the fifth stage of a series of stages which the termination of the starting cycle stages and the free piston ,engine pump is thereafter in full operation.

FIGURE 9 is an enlarged side rView, in section, of the free piston engine pump of FIGURE 3C.

FIGURE l0 is a side view, partly in section and partly broken away, of the hydraulic de-actuating mechanism of one fuel injector together with a portion of the fuel control linkage.

FlGURE l1 is an enlarged side View, partly broken away, showing the construction of one link of the deactuating mechanism of FIGURE 10.

FIGURE 12 is a longitudinal cross-section, partly broken away, of 'a hydraulic accumulator of the pressurized gas bag type.

FIGURE 13 is a diagram illustrating the `general arrangement of the electro-hydraulic control system of this invention.

Referring to the preferred embodiment shown in the drawings it will be seen that the individual components of the electro-hydraulic control system of this invention are mostly but not all of convention-al construction. However, the first portion of this specification is confined to a detailed description of each component thereof and the second por-tion is confined to the starting, operating and stopping the engine. FIGURES 3, 3A, 3B and 3C illustrate the conditions when the free piston engine pump Z185 and all components are at rest. Y

At this point it should be mentioned that the operating characteristics of the control system of this invention is predicated upon the employment of four dilferent hydraulic pressure levels. The rst pressure level is substantially equal to atmospheric pressure and comprises the drain circuit to the hydraulic iluid reservoir or sump. The second level is termed the low pressure level (eg. 200 p.s.i.) and its primary purpose is to feed hydraulic fluid inlet to the free piston engine pump 185 under suicient pressure to prevent cavitation in the engine pump 185 particularly when the engine pump 135 is operated at higher speeds. he third level is termed the highpressure level (eg. 5000 p.s.i.). It will be seen later herein that the pressure differential between the low pressure and high pressure levels is the useful or working hydraulic pressure available for propelling the l'vehicle and its hydraulic accessories or other load. i

The fourth level is termed extreme high pressure (eg. 10,000 psi.) which pressure serves to pre-position the power pistons of the engine preparatory to starting and actuate many of hydraulic components. The volume capacity of the extreme high pressure circuit is small in relation to the capacity of the lower pressure and high pressure circuits. Y

Referring to FIGURE 3 there is shown Itwo variable displacement control accumulators generally indicated at BK and CA which are of identical construction. The Vaccumulator BK is comprised of ya substantially inflexible cylindrically shaped housing 15 having an apertured end wall lo and end wall i7. Within the housing l is disposed in slidable relation a major piston 1S. Connected to the major piston 1S is a minor piston 19 which extends through the apertured end .wall 16 in slidable relation similar to that of a connecting rod or work member of a conventional fluid opera-ted cylinder or ram. The minor piston 19 protrudes or extends into an expansible spherically shaped accumulator 2l). .From this it canpbe seen that the accumulator BK has three hydraulic uid pressurizable chambers Elia, BKZ) and BKc. The chamber BKa is charged and discharged through,` port 21 in the casing l5. The chamber BKZ; is charged and discharged through port 22 and chamber Blc of the sphere .20 is charged and discharged through port 23.- IIt will be seen that the lluid volume displacement or capacity of the Vchamber Blc'ofV the sphere 2,0 is reduced'fwhen the minor piston i9 is moved leftwardly as shown` in dotted lines. The expansibility of the sphere 2t? is such that no substantial expansion occurs until the fluid pressure in chamber BKC exceeds the high pressure level (eg. over 5,000 psi.) and in addition -Will safely withstand fluid pressures exceeding the extreme high pressure level (c g. 10,000 p.s.i.).

Conventional bleed means (not shown) may be provided to exhaust air from all chambers of accumulators BK and CA to avoid air cavitation.

The purpose of lthe minor piston 19 is to vary the fluid volume capacity of the sphere 20. When the hydraulic lluid employed in the system is ordinary automatic transmission oil used commercially in automotive vehicles, an applied pressure of 5,000 p.s.i. will reduce its volume about 2 percent and at 10,000 p.s.i. its volume reduces about 4 percent. Thus under the inlluence of high pressure and extreme high pressure the hydraulic fluid exhibits an appreciable degree of compressibility. When the free piston engine hydraulic pump 135 is operating at a constant load the pistons l and 19 of the variable displacement control accumulator BK move to the right thereby increasing the fluid capacity of the sphere 2li to its maximum. lf the loadrequirement or demand is suddenly increased the major piston it immediately begins to move leftwardly and the consequent reduction in fluid volume capacity ofthe sphere 2h displaces oil which is available to meet the increased load demand during the period when the free piston engine hydraulic pump l is accelerating to meetthe demand. The accumulator EK also performs an additional function when the speed or output of the free piston hydraulic pump is `greater than the load demand which will be explained later in detail.

As mentioned previously the accumulator CA with its chamber CAQ', CAb and CAC is constructed identical with that of accumulator BK and chamber BKQ, Blb and BKL respectively, `and the elements -thereof bear the same numeral designations except they are primed.

Referring again to FIGURE 3 there are four hydraulic surge valves BP, BZ, CB and CC all of which are of the same general construction. Surge valve BP will be described and it ywill be understood that surge valves BZ, CB and CC are of Videntical construction therewith.

The surge valve BP comprises a casing 2.4i having ports 25 and 26 -as shown. Disposed centrally within the casing 24 is a Iwall or Vpartition 27 having a small calibrated restrictive passage or orifice 2S therethrough in communication with ports 2S and Zo. T us hydraulic fluid passing between ports 2S and 26 in either direction is modulated in the rate of llow due to the restriction of the orifice 28. The purpose of surge valves BP and BZ is to prevent rapid movement of the piston vlill of the accumulator BK. Likewise the purpose of surge valves CB and CC is to prevent rapid fluctuating movements of piston ES of accumulator CA.

ln FIGURE 3 there is shown a check valve CH having an inlet port 29 `and an outlet port 3i?. rilhe purpose of the check valve CH is to provide a means for dnaining hydraulic fluid from the low pressure and high pressure hydraulic circuits when the free piston engine hydraulic pump is shut down after operation. This will be explained later in detail. A

A fluid pressure operated single pole electric switch AO (FIGURE 3) of conventional 'construction is provided for ythe purpose of preventing the extreme high pressure hydraulic circuit from exceeding a maximum predetermined limit (eg. 10,500 p.s.i.) prior to or during the operation of starting the free piston engine hydraulic pump 185. The switch AO -is normal'ly open circuit and when the extreme high pressure maximum limit of hydraulic pressure at its port 31 is reached the switch is actuated to close the electric contacts thereof. When the switch AO is actuated it functions to terminate the power source for obtaining extreme Vhigh pressure hydraulic tluid prior to and during starting operations which will be described later herein in detail.

Another pressure operated single pole electric switch AM (FIGURE 3) is also provided which is constructed identically with that of the above described switch AO except that it actuates to closed position when the mini-V mum limit of ythe extreme high pressure hydraulic circuit Y (eg. 9500 p.s.i.) at port 32 is reached. The switch AM functions to prevent the operation of starting the free piston engine hydraulic pump until the extreme high pressure hydraulic circuit has attained `a predetermined minimum pressure. When the free piston engine hydraulic pump 185 is operating ythe switches AO `and AM serve no function except to keep extreme high pressure accumulator AQ charged in Icase a quick restart is ever desired as will be evident later herein.

A conventional safety relief valve A'P is provided to relieve the extreme high pressure hydraulic circuit'from excessive pressure which might occur particularly during w operation of the free piston engine hydraulic pump lSS. When the valve AP is actuated (eg. 11,060 psi.) it bleeds extreme high pressurc hydraulic luid from its inlet port 33 to its outlet port 34, the latter being communicatively connected to the hydraulic drain circuit as will be shown later herein.

As illustrated in FIGURE 3 there is an eXtreme high pressure hydraulic accumulator AQ which may be of conventional construction. it will be seen later that there are two additional accumulators AE and AI having the same general construction as that of accumulator AQ in the hydraulic system of this invention except that they function at different pressure levels. An enlarged view of the accumulator AQ is shown in FIGURE l2. In FEGURE l2 each accumulator, such as AQ, is provided with a rigidly constructed tank 35 having a flexible bag 36 positioned therein as shown. One end of the tank 35 is provided with a port 37 therethrough in communication with the inside of the ilexible bag 36 or chamber 38. Mounted externally on the tank 35 is a check valve 39. The outlet side of the check valve 39 is positioned for communication with port 37 and chamber 38. The inlet port 49 is connectable to `a source (not shown) of gas under pressure (eg. air, nitrogen, etc.) for charging the gas chamber 3d. It is preferable to use an inert gas in the chamber .33 to avoid unnecessary deterioration of the vierible bag 36. The pressure of the gas charged into the chamber 33 should be commensurate with the hydraulic pressure level to which the accumulator is to function as a hydraulic fluid accumulating means.

On the other end of the tank 35 is an hydraulic port 4l which communicates the hydraulic chamber 42 with the hydraulic circuit to which the accumulator is to function. Thus hydraulic fluid may pass through the port 4l in either direction freely. When hydraulic iluid enters the accumulator the volume of the hydraulic chamber 42 increases thereby decreasing the volume of the captive gas in the chamber 38 by compression of the gas therein to equalize the pressure in the two chambers. When the hydraulic pressure of the operating circuit decreases hydraulic uid in the chamber 42 is discharged through port 4l and the volume of the gas chamber 3S increases with a corresponding decrease in volume of the chamber 42.

Now in order to prevent damage to the flexible bag 36 when .the pressure in the hydraulic chamber 4Z falls below a minimum level, an automatic shuto valve 43 is disposed in the port 4l. The valve 43 is urged toward open position by a spring 44. However, when the pressure in the hydraulic chamber is decreased to a point where the volume of the gas chamber 33 has increased sufciently, the flexible bag .36 engages the valve element 45' and compresses the spring 44 whereby the valve element 45 seats and thus prevents further discharge of hydraulic fluid from the chamber 42. From this it can be seen `that the accumulator does not function until the operating pressure of the hydraulic circuit to which it is connected exceeds the minimum pressure in the chamber 42 at which pressure the shutol valve 43 will open.

Referring again to FIGURE 3 there is shown an electric solenoid start valve AT in `de-actuated position which valve is also shown enlarged in FlGURES 4 and 8. In FiGURE the start valve AT is shown enlarged in the actuated position. The purpose of the start valve AT is to admit extreme high pressure hydraulic fluid to energize the sequentially operated mechanism for starting systematically the free piston engine pump 185 as will be seen later in detail. in FIGURE 4 it will be seen that the start valve AT comprises a housing 45 having a spool type slidable valve element therein. The spool valve element is comprised of a pair of longitudinally spaced lands 47 Aand 48 connected to a stem 49 slidable in the housing 46. The housing 45 is provided with ports a and e registrable with land and port b registrable with land 47. The hollow portion of the land 48 is provided with a (d compression spring Ell which urges the valve spool to the position shown in FiGURES 3, 4 and 8. The ponts d and e are vents to permit movement of the valve spool in either direction and may conveniently be connected to the hydraulic drain line to recover leakage hydraulic iiuid as will be evident later.

The stem of the start valve AT extends into an electric solenoid coil Si the terminals of which are electrically connected as shown in FiGURES 3 and 3A. When the solenoid 5l of the start valve AT is de-energized (FIGURES 3, 4 and 8) the port a is closed and port b is in communication with port c. When the start valve AT is actuated (FEGURE 5) by energizing the solenoid 5i the port a communicates with port b and port c is closed.

in FlGURE 3 immediately below the above described start valve AT is an electric solenoid run-valve A] in de-actuated position which valve is also shown enlarged in ElGURE 4 in actuated position. The purpose of the run-valve Al is to control the admittance of extreme high pressure hydraulic fluid in a manner to enable the free piston engine hydraulic pump starting mechanism to function as well as operating the free piston engine hydraulic pump after it has been started, which will be explained in detail later.

Referring to FIGURE 4 it will be seen that the runvalve Al' comprises a housing 52 having a slidable spool valve element therein. The valve element comprises a pair of longitudinally spaced lands 53 and 54 connected to a stem 55. The housing S2 is provided with a port a registerable with land 53 and port c registerable with land 54 while port b is in continuous registery with the circumferential groove between lands 53 and 54 as shown. Ports d and e are vents to permit free movement of the spool valve element and may conveniently be connected to the hydraulic drain circuit to accommodate hydraulic fluid leakage.

The stem 55 of the spool valve of run-valve A] extends through an aperturein the housing 52 into a solenoid coil Se. Also a compression spring 57 is positioned in the housing 52 for urging the spool valve element rightwardly toward the de-actuated position illustrated in FIG- RE 3. Thus when the run-valve AJ is de-actuated (FiGUlE 3) port b communicates with port c while port a is closed. When the run-valve A] is electrically energized to its actuated position (FGURE 4) port cz communictaes with port b while port c is closed.

Referring to FGURE 3 directly below the above described run-valve Ai is a start position holder ram BA shown in its cle-actuated position which is also shown enlarged in FGURE 8. in FIGURE 5 the holder ram BA is illustrated in its actuated position. The purpose of the holder ram BA is to shift a mechanical linkage device 27d to the position required for starting the free piston engine hydraulic pump 135 which will be described subsequently.

Referring to FGURE 5 it Will be seen that the holder ram BA is a one-way acting, spring-loaded in a retractive direction, hydraulic cylinder. It will also be noted that the stroke of the holder ram BA is short. The construction of the holder ram BA is conventional. It comprises a casing 53 having a slidable piston 59 connected to a work member di?. A compression spring 6l is provided to urge the piston 59 and its work member @il retractively as shown in FIGURES 3 and 8. The casing 5S is provided with a port a communicable with a source of hydraulic pressure for actuating expansively the holder ram BA. Port b in the casing 5S is a vent to allow free movement of the piston 59 and may be connected to the hydraulic drain circuit to accommodate hydraulic fluid leakage.

Referring again to FiGURE 3 directly below the start position holder ram BA above described is a pressure regulator valve AU which is also illustrated in enlarged views in FlGURES 4 and 5. The purpose of the pressalones sure regulator valve AU is to control the movement of pistons lf3 and 18 of the previously described variable displacement control accumulators and CA.

The pressure regulator valve AU comprises a casing 62 having a slidable'spool valve element positioned therein. The spool valve element comprises a pair of lands 63 and A64 in longitudinal spaced relation connected together by pin 65. The outer side of land 64 is provided with a boss 66 which prevents the land 64 from abutting the rear end of the casing 62 forming a pressurizable chamber 67. A third land slidable in the casing 62 is connected to a protruding stern 69. Disposed between lands 63 and 68 is a compression spring 7l) as shown. The casing 62 is provided with ports a, b, c, d and e. Port a is the inlet for extreme high pressure hydraulic fluid and port b is the outlet therefor. Port c communicates chamber 67 with port b. Port d is a vent which may be communicatively connected with the drain circuit to accommodate leakage of hydraulic iiuid. Port e is in communication with the drain circuit.

ln operation the pressure regulator valve AU throttles the iiow of fluid into port b. Fluid under pressure entering port a passes into ports b and c. The lluid port c pressurizes chamber 67 which pressure acts to move the land 64 of the spool valve element leftwardly which throttles the flow of fluid from port a into port b and may completely close port b if the pressure is suicientiy high. As the land 6ft approaches closed position With respect to port b the land 64:- throttingly uncovers port e which permits a throttled discharge or" fluid from the chamber 57 through port e to the drain circuit. rihus port b is never completely closed but may reach a condition Where all of the hydraulic fluid passing into port b will ilow through port c and chamber 67 into drain circuit through port e. Now when the stem 69 is fully extended as in FIGURE 3 the compressive force of the spring 79 Will be at its minimum and therefore the lluid pressure in chamber 67 required to move the land 6d of the spool valve element Will be at a minimum value. However as the stem 69 is moved retractively in a progressive manner as shown in FGURES 4 and 5 the land 6d further compresses the spring 7l) which correspondingly increases the hydraulic pressure required in charnber 67 to move the land 64 of the spool valve element in a leftward direction. From this it can be seen that as the stem 69 is moved retractively the hydraulic pressure discharged through the opening 7i is progressively increased. The function of the pressure regulator valve AU during operation of the free piston engine pump will be further described in detail later herein.

Directly beneath the pressure regulator valve AU in VFIGURE 3 is a stop actuator ram AR in its de-actuated position. In FIGURE 4 an enlarged view of the stop actuator ram AR in actuated position is illustrated. The purpose of the stop actuator ram AR, when de-actuated, is to move and hold in stop position a mechanical linkage device 27? later described. When the stop actuator ram AR is actuated it enables operative movement of the above mentioned mechanical linkage device 2.7i) and thus must be actuated during the starting and operating of the free piston engine pump 185. Y

Referring to FIGURE 4 it will be seen that the stop actuator ram AR is a one-Way acting spring-.loaded hydraulic ram. Actuation of the stop actuator ram AR retracts the ram while de-actuation thereof expands it under the inuence of its spring loading. The stop actuator ram AR comprises a casing 72 (FIGURE 4) having a slidable piston 73 connected to a protruding Work member 74 positioned for abutting engagement with a portion of a mechanical control linkage device 27u described later.

Within the casing 72y of the stop actuator ram AR is a strong compression spring 75 positioned to urge the piston 73 and associated work member 7d in e 'pansive direction. lt is emphasized that the compressive characteristics of the spring 75 should be high for, as will be evident later, when the ram AR is de-actuated the spring 75 must exert a orce sufficient to overcome certain counter forces. The casing 72 is provided With ports a and b; the port a being communicatively connected to the hydraulic drain circuit and port b is for pressurizing the chamber 76 to actuate the ram AR retractively.

ln FGURE 3 positioned to the immediate right of the solenoid start valve AT is a shut-oli valve BB. The purpose of the shut-off valve BB is to terminate the ilow of extreme high pressure hydraulic iluid to certain other valves, later described, and communicating these other valves with the hydraulic -drain circuit. The shut-olf valve BB is shown de-actuated in FGURES 3 and 5 and actuated in FIGURE 7.

rI'he shut-off valve BB comprises a housing 77 (FG- URE 5) having a slidabile spool valve element therein. The spool valve element has three lands 78, 79 and 80 in longitudinal spaced relation on stem 81 as shown in FGURE 5. A compression spring 82 is positioned to urge the lands 78, 79 and 89 with the Istem 3l. in a right- Ward direction as viewed in FIGURE 5. The housing 77 is provided with ports a, b, c, d, e and f. The land 78 is registerable with port e and land 79 is registerable with port a while land 89 is registerable with port d. Port c leads to chamber 83 which chamber when pressurized actuates the shut-oil valve BB to the position illustrated in FIGURE 7. The port f is a vent and may be connected to the hydraulic drain :circuit to accommodate leakage. In the de-actuated position shown in FIGURE 5 port fz communicates lwith port b while port e is closed. in the (le-actuated position no iluid iiow occurs in port d because it is not in communication with any other port. The port d is connected to the hydraulic drain circuit to remove any lluid leakage at the land 79 as otherwise such leakage may also leak past land Sti thereby pressurizing the chamber S3 and prematurely act-nate the shut-oil valve BB. -n the actuated position in FIGURE 7 port e communicates With port b While port a is closed.

Positioned immediately below the shut-oli valve BB in FIGURE 3 is a first sequence valve BC in de-actuated pc ition. It is also shown in the cle-actuated position in FiGURE 7. FEGURE 5 illustrates the sequence valve BC alter it has begun to actuate but insucien; to alter flow communication through its ports from that of its completely deactuated position. ln FlGURE 6 the sequence valve BC is completely actuated. At this time it is pointed out that the actuation of sequence valve BC requires the elapse of an appreciable time for reasons explained later herein. The purpose of the sequence valve BC is to provide a time differential to allow certain components to actuate and perform their respective functions prior to the actuation of certain other components which will be discussed later in detail.

Referring to FIGURE 5 the sequence valve BC comprises a housing 8l having a spool type slidable valve element. rlhe spool valve element comprises a pair of lands S5' and 3d mounted in `longitudinal spaced relation on stem 37 as shown. A compression spring S8 is positioned for urging the valve element in the rightWard direction as viewed in FiGURE 5. The housing 84 is provided with ports c, b, c, d, e and f as shown. In the de-act-uated position port a communicates :with port b While port c communicates with port e and ports d and f are closed. Port e communicates with the hydraulic drain circuit. lIn the actuated position (FlGURE 6) port c is closed While port z communicates with ports b, d and f.

back to 5 it will be seen that the land S6 of sequence valve BC is provided With longitudinal holes or orifices 39 extending therethrough. The orilicesk thus communicate chamber 9d with chamber 9i Thus when the chamber' 9@ is pressurized fluid passes through the orifices 89 and pressurizes chamber 91. The pressurizing of chamber 9i will move the valve element leftwardly to further compress the spring 88. The number and diameter of the orifices S9 in the land d6 are important and should be chosen in accordance with the viscosity and pressure of the hydraulic fluid to govern the rate which the fluid passes through the orifices into chamber 91. The objective here is to permit a predetermined minimum time elapse after pressurizing chamber 99 before the valve element alters the port communications. Thus in effect the sequence valve BC is a time delay valve.

In FIGURE 3 to the right `of the above described sequence valve BC is a drain valve BD shown in its deactuated position. It is also shown in de-actuated position in FIGURES 5 and 7 but actuated in FIGURE `6. The purpose of the drain valve BD is to permit a pair of one-way acting rams, not yet described, to de-actuate after their respective functions have been performed which will be described more in detail later.

Referring to FIGURE 5 the drain valve BD comprises a casing 92 having a spool type slidable valve element disposed therein. The valve element comprises a pair or" longitudinally spaced Ilands `93 and 94 mounted on a stem 9S. A compression spring 96 is mounted within the drain valve BD positioned for urging its valve element in a leftward direction as viewed in FIGURE 5 rihe casing 92 is provided with ports cz, b, c, d and e. When the drain valve BD is de-actuated port a communicates with port b while port d is closed. Port e is a vent. rihe valve BD is actuated by pressurizing chamber 97 through port c and When actuated (FIGURE 6) port b `communicates with port d while port a is closed.

In FIGURE 3 directly beneath the previously described sequence valve BC is a snap action loch valve El shown in its tie-actuated position. 'l' he valve Bl is also shown deactuated in FIGURE 6 and actuated in FIGURE 7. The purpose or" the lock valve BI is to maintain in actuated position the thermo-compensated Valve AY (later to be described) while the free piston engine hydraulic pump 1185 is in running operation. Thus the loch valve El will be in actuated position when the engine pump l is running.

Referring to FIGURE 6 the lock valve BI comprises a casing 9S having a spool type slidable valve element disposed therein. The valve element comprises a stern having three longitudinally spaced lands lili?, ldl and lli?. as shown. A compression spring E63 is positioned to urge the valve element in a rightward direction as viewed in FIGURE 6. It will be observed that the land 24.92 is smaller in diameter than lands itl@ and itil. Likewise the bore in the casing 98 slidably supporting the land lli?) is smaller than the bore supporting lands itl@ and lill. The casing 98 is provided with ports a, b, c, d, e and f as shown. Ports e and f communicate with the hydraulic drain circuit. When the loch valve El is de-actuated port a communicates with port b and port d is closed. Port e communicates with chamber ltll and port c communicates with chamber lib'. When the chamber llt-*9S is pressurized through port c the valve element shifts leftwardly to the actuated position illustrated in FlGURE 7 wherein port b communicates with port d and port e is closed. When the lock valve Bl is actuated, port a has no i'luid llow because it is not in communication with any other port of the lock valve BI.

In the actuation of lock valve Bl the pressurized duid in chamber 10S acts on the small land JBZ as a piston which then moves the valve element in a leftward direction. When the valve element has moved leftward sufciently to close port e and open port d the chamber 164 becomes pressurized which in turn acts on the larger diameter land lill to impart a greater impetus for cornplete actuation. Thus it requires a higher iiuid pressure at port c to initiate actuation than required to maintain the valve in actuated position once it has been actuated. Furthermore when the land 10i uncovers port d the rate of leftward movement of the valve element is greatly accelerated and thus a snap action result occurs.

Referring again to FIGURE 3 positioned to the right of the above described snap action lock valve B3 is a CII lil

hydraulic ram return valve BE in tie-actuated position also illustrated in FIGURE 6. in FIGURE 5 the return valve BE is shown in actuated position. The purpose of the return valve BE is to permit a pair of one-way acting hydraulic rams, described later, to retract to de-actuated position when their respective functions have been accomplished.

Referring to FlGURE 6 the return valve BE is of the slidable spool type comprising a casing ille having a slidable valve element there: The valve element comprises a pair of longitudinally spaced lands l07 and 108 supporting a stem lill). A compression spring liti is disposed in the casing 106 positioned to urge the valve element rightwardly as shown. rhe casing M6 is provided with ports a, b, c, d, and e as shown. The port a is the inlet means for pressurizing the chamber lll whereby the valve element is actuated to a lettward position illustrated in FlGURE 5. When the return valve BE is de-actuated (FIGURE 6) port b communicates with port c while port d is closed by the land itl?. Port e is a vent communicatively connected to the hydraulic drain which permits free movement of the siidable valve element. When the return valve BE is actuated (FlGURE 5) the port c communicates with port d while port b is closed by the land lil. When fluid pressure in chamber lli is relieved the compression spring litt returns the valve element to its cle-actuated position shown in FIGURE 6.

Referring back to FIGURE 3 to the right of the above described hydraulic return valve BE is another sequence valve EO shown in de-actuated position which, except for location of its ports, is constructed similar to the sequence valve BC previously described. The sequence valve BO is also shown in FIGURE 6 in cie-actuated position while FEGURE 7 illustrates it in actuated position. The purpose of the sequence valve BO is to maintain the previously described lock valve BJ in actuated position while the free piston engine hydraulic pump TISS is in running operation and also controls actuation of the previously described shut-olli valve BB.

Referring now to FGURE 6 the sequence valve BO comprises a housing il?. having a spool type valve element slidable therein. The valve element comprises a pair of longitudinally spaced lands M3 and lid supporting a stem as shown. The housing M2 is provided with ports a, b, c and ci as shown. When the sequence valve B0 is de-actuated (FIGURE 6) port a communicates with port b while port c is closed by the land 114. When the sequence valve BO is actuated (FIGURE 7) ports a, b and c are in communication with each other as shown. Port d is a vent in communication with the hydraulic drain circuit to facilitate tree movement of the valve element and to accommodate hydraulic iluid leakage which may occur. The compression spring M6 in the housing lli is positioned to urge the valve element toward deactuated position illustrated in FlGURE 6. Now the land ll is provided with at least one longitudinal passage il@ therethrough for communicating chamber il? with chamber lig. Similar as that already described for sequence valve BC when l'luid pressure in chamber M7 increases it seeps into chamber ll through passages 119 thus elevating the iluid pressure in chamber HS. As the pressure rises in chamber lid it acts on the lands il?) and i14- to move the valve element rightwardly from the dewactuated position shown in FIGURE 6 to the actuated position shown in FIGURE 7. However, the rate of movement of the valve element is relatively slow which, as in the case of sequence valve BC previously described, allows an appreciable time period to elapse after the start of actuation until port communications are altered. lt will be seen later that this time delay period serves an important function and for this reason the aggregate cross-sectional area of the passages 119 in land 113 Should be carefully chosen.

In FIGURE 3 directly below the above described hydraulic ram return valve BE is a snap action thermocompensated valve AY shown in tie-actuated position. It

is also shown in cle-actuated position in FlGUi?.E 4 and in actuated position in FlGURES 6 and 7. The primary purpose of the thermo-compensated valve AY when actuated is to communicate the chamber BKL' with the free piston engine hydraulic pum ldd whereby extreme higi pressure hydraulic lluid delivers an impulse for starting the engine. The secondary purpose of the valve AY is to actuate the previously described lock valve Bl as will be described later in detail.

Referring to HGURE 4 the thermo-compensated val AY is or" the slidable spool type comprising a housing having a slidable spool valve element disposed therein. The valve element comprises four lands lfil, E22, 1.23 and T124 as shown. The land L21 is of relatively small diameter slidable in a small bore of ti e housing frle? while lands 22, T123 and E24 are of larger diameter in a large bore in the housing "129. The lands to l are positioned in longitudinal spaced relation by the sten M5. Disposed in the chamber 126 of the housing lili? is a large compression spring 127 positioned for urging the valve element leftwardly as viewed in FGURE 4.

Disposed in the leftward end portion of the housing 12@ of the thermo-compensated valve AY is a conventional gas bellows 212B Which bellows urge a slidable piston 129 in a rightward direction. Disposed within the chamber 13@ in the housing 12o is a small compression spring 131 which urges the slidable piston i3?. in a rightward direction. The housing lill is provided with ports a, b, c, d, e, f, g, lz, z' and j as shoui. When the valve Y is `tie-actuated port d corrmiunicates with port e While ports a and g are closed by land 15.24, port f is closed by land 123 and port c is closed by land Z. Ports 1'1, i, and j are in communication with the hydraulic drain circuit at all times. When the valve H actuated A1 1S (FIGURE 7) port c communicates with port d; port e communicates with port f and port a communicates with port g while port j is closed by the land mi.

Actuation of the thermo-compensated valve AY is accomplished in a similar manner as that previously described or lock valve El. ln the valve AY extreme high pressure is admitted through port b and hydraulically Iacts on the small diameter land Qd. As soon as the valve element has moved rightwardly sulliciently lthe land E21 closes port j and the land 122 begins to uncover port c. Extreme high pressure hydraulic fluid thus enters chamber i133 and acts on the land 122 which quickly moves the valve element into its actuated position as illustrated in FGURE 7. From this it is apparent that a higher fluid pressure is required to actuate the valve AY than that required to maintain it in actuated position after initial actuation. Furthermore the port consimunications are shifted rapidly.

The valve AY is also designed such that the fluid pressure required for actuation varies inversely with lthat of the ambient temperature. The force exerted by the gas pressure in the bellows 23 plus the compressive force of spring lS offsets a portion of the force exerted by the spring 127. Since gas expands with a temperature rise, the gas pressure in the bellows correspondingly rises which then moves the piston ,lf/1.9 rightwardly (FGURE 4) to further compress the spring lili. This further cornpression of the spring i3d correspondingly increases the force on piston 132 which hears upon the leftward end of stem 125 of the valve element. The resulting increased force on the stem 125 odsets a portion of the opposing force by the spring v27. The net effect is that Where the ambient temperature is elevated the pressure of the hydraulic fluid entering port b required to initiate actuation of the valve element will be less than that required to initiate actuation when the ambient temperature is lowered. lt will be observed -in comparing the valve AY in FIGURE 4 (deactuated) with that of *lGl RE 7 (actuated) the piston or plate SZ bears against the leitward end of the stem lid until the land l2?. begins to onen port c at which point the plate 13.?. abuts the housing As stated above, the actuation of the thermo-compensated valve AY permits the delivery of extreme high pressure hydraulic duid impulse for starting the free piston engine hydraulic pump ld. Since it is common that an internal combustion engine requires a greater amount `of energy for starting in cold weather than that required for warm weather, the thermo-compensated valve AY automatically performs the function ofv requiring a higher hydraulic fluid pressure for cold weather starting than that for warm weather. inus it is apparent that the characteristics of the springs 112:7 and lfl -as well as that for the bellows 'A28 should be carefully chosen so that the valve AY will function throughout the temperature range under which the engine pump ldd may be started. When the engine pump 5.85 is in running operation the valve AY is in actuated position at which time the thermal characteristics are of no effect.

ln FIGURE 3 directly beneath the above described thermo-compensated valve AY is` a pair of hydraulic rams BG and BF in de-actuated `position. The rams BG and BF are also shown in de-actuated position in FIG- URE 6 while ElGURE 5 illustrates them in actuated position. The hydraulic rams BF and BG are conventional one-way acting springloaded in fa retractive direction. The hydraulic ram BG herein is the hydraulic ram 'T158 shown in FEGURE 8 of the above mentioned copending application. Likewise the hydraulic ram BF herein is the hydraulic ram lid?? shown in FlGURE 4 of the aforesaid copending application.

Referring now to FIGURE 6 of the present application the hydraulic ram BG comprises a housing 1.34 having a slidable piston i3d connected to Work member loo as shown. A compression spring 37 is positioned in the housing i3d for urging the piston i3d and its associated vwork member i3d in a retractive direction. The housing 3d is provided with ports a and b as illustrated. Hydraulic pressure entering port a actuates the ram BF expansibly. Port b is primarily a vent but, -as will be seen later, may be pressurized to make certain that the ram BG is retracted when the free piston engine hydraulic pump ESS starts. The purpose of the hydraulic ram BG is to close the start cycle control valve BH, later described, and cock a toggle device ld? also later described.

The hydraulic ram when actuated serves to preposition the pou/er pistons of the free piston engine hydraulic pump preparatory to starting. 'Ehe ram BF comprises a casing E38 having a slidable piston 139 connected to a work member lf2-G- es shown. A compression spring lill is disposed in the casing i323 positioned to urge retractively the piston E39 and its associated work member as shown. he casing E33 is provided with ports a and b as illustrated. Hydraulic pressure entering the port a actuates the ram BH expansively to the position shown in E GURE 5. ll'he port b is primarily a vent but may oe pressurized to malte certain the ram BF is retracted as will be described later. The rams BF and BG are hy raulically connected in parallel as will be evident later herein. When the ram BF is actuated the externally protruding end lli-i2 of the -work member 35,45 abuttingly engages a rack member 43 in FIGURE 3 (also shown as rack `member 14,3 in FIGURE 4 of the aforesaid copending application. The rack member 143 is in meshed relation with the pinion led (illustrated as pinion M2 in Fl-GURE 4 of the aforesaid copending application) ywhich pinion is connected to the synchronizing mechanism for the power pistons of the free piston engine hydraulic pump iS. Actuation of the ram BF thus pre-positions the power pistons of the free piston engine hydraulic pump ld preparatory to starting as fully described in the aforesaid copending application, reference thereto being had.

ln FIGURE 3 immediately to the left of the above described hydraulic ram BG is a start cycle control valve Bil in cle-actuated or open position. ln FlGURES 5 and 6 the valve BH is shown in actuated or closed position.

The purpose of the start cycle control valve BH is to prevent communication of hydraulic fluid between the upper unit A of the free piston hydraulic pump 185' and the hydraulic working circuit during the period when an impulse of extreme high pressure hydraulic fluid is delivered to start the engine pump 135. The valve B-I is the same as the valve 13S illustrated in FIGURE 8 of the aforesaid copending application.

Referring to FIGURE the start cycle control valve BH comprises a housing 145 havhlg a slidasle spool type valve element therein. The valve element comprises a pair of longitudinally spaced lands 146 and 147 connected to a stem 148 as shown. The valve BH is positioned in axial alignment With hydraulic rarn BG previously described. The housing 145 is provided with a longitudinal bore adapted to accommodate slidably the work member 136 of the ram BG for abutting engagement with the rightward end of the stern 14S as shown in FlGURE 5. The housing 14S is provided with ports a and b, the port a being an inlet port and port b being an outlet port. Ports c and d in the housing 145 are vents and if desired may be connected to the hydraulic drain circuit to accommodate hydraulic lluid leakage. When the valve BH is actuated as shown in FIGURE 6 the land 147 closes the inlet port a and thus no fluid flows out through the outlet port b. In the de-actuated position of the valve BH as shown in FIGURE 3 the inlet port a communicates with the outlet port b.

In FIGURE 3 at 149 is indicated a toggle device in the de-actuated or uncooked position. In FlGURES 5 and 6 the toggle device 149 is shown in the actuated or cocked position. The toggle device 149 functions in the same manner as the toggle device 174 in FIGURE 8 of the aforesaid copending application.

Referring to FIGURE 5 the toggle device 149 may conveniently comprise a rod having one end thereof pivotally connected at 151 to the protruding portion of the stem 148 of the start cycle control valve Bl-l. Pivotally connected at 152 on the other end of the rod 15% is a toggle lever 153 having a roller 154 mounted on one end thereof as shown. The other end of the toggle lever 153 is pivotally connected at 155 to a stationary member (not shown). A tension spring 156 is provided having one end connected to the lower portion of the toggle lever 153 and the other end connected to a stationary member (not shown).

The toggle device 149, start cycle control valve 3i-I and the hydraulic ram BG are mounted in alignment as shown in FIGURE 3. From the uncoclred position in FIGURE 3 the ram BG 4is actuated to the position shown in FIGURE 5 which pushes the stem 14S of the valve BH thereby closing communication between ports n and b thereof. In turn the stern `14e of the valve BH pushes the toggle lever 153 of the toggle device 149 to move the roller 154 to the left of dead center with reference to the tension spring '156. Thereafter the hydraulic ram BG retracts leaving the valve BH in closed position and the toggle device 149 in cocked position. As viewed in FIG- URE 6 it can be seen that if the roller 154 of the toggle device 149 is moved rightwardly to a point just past dead center lwith reference to the spring `155, the valve BH will be opened by snap action, due to the force of the spring 156, to the position illustrated in FIGURE 3. Means will now be described for tripping the cocked toggle device 149 to the uncocked position.

ln FIGURE 3 adjacent the toggle device 149 is a cam 157 having a looe 158 mounted on a shaft 159. The cam 157 corresponds to the cam 134 illustrated in FGURE 4 of the aforesaid copending application. The shaft 15d is part of `the mechanism for synchronizing the movement of the power pistons in the `free piston engine hydraulic pump 185 which mechanism is described in detail in the aforesaid copending application reference thereto being had. It is sucient to say that in starting the engine UJI ld pump '155 when the upper pair of power pistons moving on initial fuel-airrcompression stroke reaches ignition position (i.e. initial firing) the lohe 15S of the cam 157 will have moved into engagement with roller 15dn of the toggle device y149 and shifted the toggle lever 153 sufficiently beyond dead center position thereby tripping the toggle device 149 back to the uncooked position illustrated in FIGURE 3. Further details of the toggle device 149 will be described later herein.

Referring now to FIGURE 3A there is a conventional rotary type hydraulic motor CD having its output shaft connected to the input element of a conventional overrunm'ng clutch 161i. The output element of the clutch 16) is connected to the shaft of a conventional electric motor MA. The shaft of the electric motor MA is also connected in drive relation with a conventional extreme high pressure hydraulic pump AH. The inlet for the pump AH is at port a and the outlet is at port b thereof. The inlet for the tydraulic motor CD is at port a thereof and the outlet is at port b. It should be apparent that if the electric motor MA is energiaed it drives the extreme high pressure hydraulic pump AH but does not drive the hydraulic motor CD due to automatic disengagement of the overrunning clutch 160. However, when the hydraulic motor CD is pressurized from the high pressure hydraulic circuit through port a the clutch engages thereby driving the extreme high pressure hydraulic pump AH through the electric motor MA which electric motor is then de-energized as will be further explained later. The purpose of the pump AH is to provide the source for extreme high pressure hydraulic lluid required for starting and operating the free piston engine hydraulic pump 13S according `to this invention. It is also pointed out that the capacity output in volume of the pump AH need not be large as will be evident later herein.

In FEGURE 3A the start key switch Y is a conventional single pole electric switch which is mounted on the instrument panel of the tractor (FIGURE 2) positioned for convenient access to the operator. The switch Y may only be closed electrically by the insertion of the key 161 and thereafter rotating same in a similar manner as that of a conventional ignition switch employed on most motor vehicles. Thus, as will be evident later herein, the tractor of FGURES 1 and 2 is inoperative unless the switch Y is closed by the insertion and operation of the key 1x51 therein. As will be described later in detail, when the start key switch Y is closed it serves to energize the single pole normally open start key relay switch C to its electrically closed position. Closing of switch C energizes the electric motor MA and actuates the solenoid run valve A] previously described. In addition it also energizes the electric motor M (FIGURE 3B) for driving the free piston engine pump accessories described later.

Immediately above the start key switch B in FIGURE 3A is a single pole normally open start button switch AZ. The switch AZ is mounted near the switch Y on the tractor as indicated in FGURE 2. When the button 162 is depressed by the operator at the proper time the switch AZ electrically closes which serves to energize the start button relay switch AZI. The relay switch AZI is a single pole normally open switch. When energized it closes which in turn energizes the solenoid start valve AT in FIGURE 3 (previously described) to actuated position.

Also in FIGURE 3A is a conventional electric storage battery Z which provides the electric energy necessary to start and operate the free piston engine hydraulic pump according to this invention. A conventional voltage regulator BT is provided to govern the electric charging of the battery Z by the generator G (FIGURE 3B) when the free piston engine pump is in operation.`

In FGURE 3A there is a single pole normally closed motor cutout relay switch AK. The relay switch AK is energized to open position when the high pressure switch AO in FIGURE 3, previously described, is actuated to closed position. The purpose of relay switch AK is to de-energize the motor MA when the extreme high pressure hydraulic circuit reaches a pre-determined upper limit set by the high pressure switch AO.

Also in FIGURE 3A is a low pressure cutout relay switch AN. The relay switch AN is a single pole normally open switch. The relay switch AN is energized to closed position when the low pressure switch AM in FlGURE 3 (previously described) is closed. The purpose of relay switch AN is to prevent energizing the solenoid start valve AT when the hydraulic pressure in the extreme high pressure circuit is below the limit set for actuation of the low pressure cutout switch AM. In effect this prevents the operator from attempting to start the free piston engine hydraulic pump ldd when the uid pressure in the extreme high pressure hydraulic circuit is insuilicient and is accomplished by opening t .e electrict circuit, through relay switch AN, to the start button switch AZ.

ln FIGURE 3A is a relay switch X having single pole normally closed contacts BU and single pole normally open contacts BS as shown. ln the (le-energized position shown the contacts BU are closed which condition permits energizing the motor M (FIGURE 3B) when the start lrey switch Y is closed. YWhen the free piston engine hydraulic pump T135 has started the generator G rotates at a speed sulhcient to deliver a voltage high enough to charge the battery Z, the charging voltage from the generator G (Fl'GURE 3B) thereupon energizes the relay switch X to actuated position. In actuated positon the contacts BU open which de-energizes the motor M (FIGURE 3B). At the same time the contacts BS close which connects the generator G with the battery Z through the previously described voltage regulator BT. Thus when the free piston engine pump 185 is in running operation the battery Z is re-charged.

Also in FIGURE 3A is an extreme high pressure pump motor cutout relay switch CE. The relay switch CE is a single pole normally closed switch. The relay switch CE is energized to open position by the generator G (FIG. 3B) and is actuated at the same time as that of the above described relay switch X. The purpose of the elay switch CE is to de-energize the motor MA when the free piston engine hydraulic pump 25.85 is in running operation.

Grouped together in FEGURE 3B are the accessories for the free piston engine hydraulic pump An electric motor M, powered by the battery Z may be connected conveniently in drive relation by means of common shaft 153 to a hydraulic charge pump ZA, lubricating oil pump H, fuel pump O, coolant water pump V, and fan U as shown. The pumps ZA, l-l, O and V may be orn any suitable conventional design. The motor M and shaft are also drivenly connected to the output element of an over-running clutc i6-. An electric generator G is drivingly connected to the input side of the clutch 16d and the output shaft of a rotary type hydraulic motor BQ. Thus when the electric motor M is energized it drives the pumps ZA, l-l, O, V and fan U but does not drive the generator G or de-energized hydraulic motor BQ. When, however, the free piston engine hydraulic pump lSS is in running operation, the hydraulic motor BQ becomes energized, as will be explained later, which then crives the generator G as well as pumps ZA, H, O, V and fan U. Thus as the hydraulic motor BQ overtakes the motor M the generator G actuates, as will be ecalled previously, the relay switch X which actuation de-energizes the electric motor M and thereafter the engine accessories are powered by the hydraulic motor BQ.

The purpose of the hydraulic charge pump ZA is to lill the entire hydraulic system with hydraulic fluid and to replenish hydraulic fluid lost from the various circuits through leakage or otherwise. Thus the capacity oi the hydraulic charge pump ZA need not he large but must 3.5 be capable of delivering hydraulic iluid at a pressure somewhat greater than that of the low pressure hydraulic circuit (eg. 209 p.s.i.). The hydraulic charge pump ZA receives hydraulic iluid from the hydraulic fluid sump XA through a p imary hydraulic filter YA by means of conduits 2h35 and 166 as shown. The outlet side of the hydraulic charge pump ZA communicates to the conduit 67 through a secondary hydraulic liuid filter AA and hydraulic fluid heat exchanger W (for heating or cooling the hydraulic lluid as may be desirable). A conventional pressure relief valve AB is connected to the conduit 167 for the purpose of limiting the discharge pressure of the pump ZA which permits the by-passing of excess huid pressure back to the sump ZA through the conduit lh.

The conduit 167 from the charge pump ZA leads to the inlet sides of a pair of check valves AC and AD as illustrated in FlGURE 3B for purposes to be described later.

The lubricating oil pump H is a means for lubricating under pressure the free piston engine hydraulic pump The pump H draws lubricating oil from the lubricating oil sump F through a primary oil filter GA by means of conduits 7169 and 76 as shown in FIGURE 3B. The outlet side of the pump H communicates with conduit 171 through a iilter lA and lubricating oil heat exchanger J (for cooling the oil). A conventional pressure relief valve K is provided to bypass lubricating oil at excessive pressure to the sump F through conduits 17251 and i7?. as shownA The relief valve K is thus a means for limiting the maximum pressure of lubricating oil delivered to the free piston engine pump 185.

The fuel pump O is a means for delivering fuel under pressure to the fuel injectors 2id-2M (FIGURE 3C) of the free piston engine hydraulic pump 185. The fuel pump O draws fuel from the fuel tank MB through a filter N by means of conduits 173 and 174 as shown in FIGURE 3B. The outlet side of the fuel pump O communicates with the conduit 1175 through conduit 176 and tllter P. A conventional pressure relief valve Q is connected to the conduit 2175 to limit the maximum fuel pressure delivered to the injectors E14-2U by bypassing fuel at excessi e pressure back to the fuel tank MB by means of conduit i7?.

The purpose of the water pump V is to provide means for circulating water to cool the above mentioned heat exchangers l and W and the coolant jackets in the free piston engine hydraulic pump 1185. The water pump V draws water from t e Water tank S through a conventional radiator or air cooled heat exchanger T by means of conduits 17S and 179 as shown. The outlet side of of the water pump J is connected to the conduit 180. The conduit lu'i thus communicates cooled Water into the serially connected conventional heat exchangers W and l to the conduit 131. The conduit 181 is connected to the inlet side of the coolant system in the free piston engine hydraulic pump ld later described.

ln FlGURE 3E there is shown a low pressure accumulator AE which is constructed similar to that of the extreme high pressure accumulator AQ (FlGURES 3 and l2) previously described except it is operative at the pressure of the low pressure hydraulic circuit (eg. 2G() p.s.i.). The low pressure accumulator AE is communic'atively connected to conduits idr., 1&3 and ld as shown. The purpose of the low pressure accumulator AE is to receive and store hydraulic fluid discharged from the various hydraulic motors (ie. work load) energized by the high pressure hydraulic huid and to return the iluid to the inlet side of the free piston engine hydraulic pump 'i135 under pressure (eg. 200 p.s.i.). Also it serves to smooth or absorb pressureV fluctuation and supply sudden demands for fluid.

The check valves AF and AG (FIGURE 3B) are provided to prevent reverse flow of hydraulic uid in the con-suits and 2551.1 which would otherwise o cur when the pumps in the free piston engine hydraulic pump 155 

1. A STARTING SYSTEM FOR STARTING A FREE PISTON ENGINE HAVING AT LEAST ONE POWER PISTON OPERATIVELY CONNECTED TO A HYDRAULIC PUMP COMPRISING: A SOURCE OF HYDRAULIC FLUID OF EXTREME HIGH PRESSURE, A HYDRAULIC POWER MEANS ENERGIZED FROM SAID SOURCE POSITIONED TO MOVE SAID POWER PISTON SUBSTANTIALLY TO A POSITION WHERE IT BEGINS ITS FUEL COMBUSTIVE MIXTURE COMPRESSION STROKE, A HYDRAULIC FLUID ACCUMULATOR CHARGED WITH HYDRAULIC FLUID OF EXTREME HIGH 